The disclosure relates to methods and devices for detecting defects in a transparent body. Particularly, the disclosed embodiments relate to methods and devices for detecting defects in a transparent product such as a glass panel or a lens using an existing optical dimension measuring apparatus.
A technique of using a plurality of light sources, as disclosed in WO 2010/133341A1, for example; a technique of detecting deflection or polarization caused by defects, as disclosed in EP 2253949A1; a technique using a laser interferometer; and a technique of using a contour shape measuring apparatus, such as that disclosed in Japanese Unexamined Patent Application Publication No. 2002-131041A and Japanese Unexamined Patent Application Publication No. 2003-156326A, can all be given as techniques to examine for defects in a glass product, such as a glass panel or a lens, or a transparent plastic product.
Additionally, the laser scanning-type dimension measuring apparatus disclosed in Japanese Patent No. 4162426B and Japanese Patent No. 4191953B (also called a “laser scan micrometer”), and the image sensor-type dimension measuring apparatus disclosed in Japanese Patent No. 5507879B (also called an “image sensor-type micrometer”), which were proposed by the applicant of the present embodiments, are examples of optical dimension measuring apparatus that can be used to measure the outer diameter of a pin gage or a plug gage for measuring the diameter of a hole in an object.
Furthermore, in Japanese Unexamined Patent Application Publication No. H09-138115A, the applicant of the present embodiments has proposed a technique for measuring a transparent body using the aforementioned laser scanning-type dimension measuring apparatus.